The purpose of this study is to investigate the effectiveness of Virtual Environment Desensitization (VED) in combating acrophobia (fear of heights). VED has the advantages of conducting time-consuming exposure therapy in the therapist's office and giving precise control of stimuli. Thus it may offer a time- and cost-effective mode of therapy, with implications for the treatment of many disorders, especially anxiety disorders. While the results of previous VED research projects have been consistently positive, this project will involve a much larger number of subjects, significantly increasing the confidence which can be attached to any positive findings. This study will also include is (Imaginal Systematic Desensitization) and PDW (Programmed Distance Writing) control groups in addition to the no-treatment control group used in the previous studies. Subjects will consist of at least 120 college undergraduates. They will undergo an extensive screening process to insure that they are suffering from acrophobia, and do not have any other serious physical or psychological conditions. Subjects' degree of fear anxiety will be measured using several subjective instruments; and physiological instruments will be used to measure various changes in bodily functions. Computer modeling will be created using Meme virtual reality development software package to develop several virtual reality development software package to develop several virtual reality scenes for VED group. The treatment schedule will consist of eight weekly sessions for the IS, PDW, and VED conditions. Assessment measures will be administered to all subjects pre-treatment, post-treatment, and one month post-treatment.